Well and update I had reflashed my demo kindle and accidentally overwritten the area of the MMC that stores the S/N and MAC. I don't have the box any more so thought I was screwed!

While trolling the forums for ideas I found a thread where someone had a cracked screen and need to find out the serial number and someone suggested connecting it to the PC and reading the serial from device manager - which game me an epiphany!

I used USBDeview to lookup up the data of all USB devices installed on my computer and there it was! yay!

Using the MAC from another kindle the device is able to connect to Wifi but it is unable to register, or possibly it is unable to register due to the previous incorrect serial number being deregisted where this serial hasn't been resulting the kindle thinking it is deregisted when it isn't.

now I just need to figure out how to update the PCBA ID, and hopefully get the MAC from Amazon Support!

Well, there is data in the device dependent configuration stored in the flash section that also has MAC and serial number. I didn't bother to investigate yet, but that's basically why I've chosen to never publish the device config from my device even with blanked MAC and serial number (and if I zeroed out everything, it would not be of much worth anyway...).

actually hawhill i've noticed that if the other ID's are missing/garbled it'll refuse to register, i duplicated that by flashing the Bad dump i hadfrom my dead (and now gone) kindle to teh new one. Sure as ***t it would error durring reg but everything else worked. restored the backup and it resumed like it was just turned off all this time.

Tried it twice, carefully following the instructions each time, to no success.
When it got to flashing the kernel it spent a long time on 'waiting for device'
then changed to success without any progress or anything in between, then when it went to flash the main partition it stayed on 0% for a couple mins then said finished...It was suppose to take 1-3 hours.
From the little I've gathered I think I broke the bootloader. (how to fix if so?)
I haven't gotten the screen to do anything for a while and nothing ever happens with the LEDs without it being plugged in (turns orange).

It's a kindle 3 keyboard by the way (wifi only). I had some hacks installed ages ago but I haven't messed with it in a long time since.

But I think it is also what's being used in Kubrick. So it will probably expose the same behaviour. I don't think that breaking the device via ATK is easily possible. Then, I'm skeptical why the poster was able to use "0x..." in the ATK input field - the "x" isn't a valid hex char and I think ATK wouldn't work in such a case. So I guess the error report misses some parts. Maybe they involved frying the USB port on either the Kindle or the Host, maybe it's just a bad USB cable. Don't know. Or it might simply not been put into USB downloader mode properly again. I'd suggest to hang on to Kubrick (to rule out other error possibilities) and try with other USB ports and cables.